The process of fabricating a depletion mode NMOS transistor during the standard process of fabricating a CMOS device by extending the source and drain regions of the transistor into the gate area.
A depletion mode NMOS transistor is a useful device in some applications such as an input noise reduction circuit or an input gate protection device. However, to build one such a device on a CMOS device using the regular CMOS process would normally require changes in the mask layers and process sequence. The capability of building NMOS depletion mode transistors in an otherwise standard CMOS circuit using the standard CMOS process would be a significant advantage.